The role of relative age effects in generic motor skill diagnostics using the German motor test (6–18): diagnostic outcomes and recruitment of 9–10-year-old children to sports schools in Germany

Introduction Generic motor skill diagnostics are widely applied in early talent identification alongside anthropometric and sport-specific performance measures. However, talent selection processes in youth sports are frequently influenced by relative age effects (RAEs), which are closely linked to diagnostic procedures and recruitment practices. Methods This retrospective analysis examined associations between calendar age and motor performance in a large cohort of German fourth-grade schoolchildren ( N = 19,179; aged 9–10 years). All participants completed the German Motor Test 6–18 (GMT 6–18) between 2008 and 2022 as part of the diagnostic process for recommendations to North Rhine-Westphalia (NRW) Sports Schools, a combined school and competitive sport system. Motor performance differences were analyzed using analyses of variance, reporting F- values, p- values, and effect sizes (η 2 ). Furthermore, generalized linear models (GENLIN) were applied to examine associations while accounting for covariates and to support the robustness of the findings. Recommendation and admission rates were assessed using Pearson's chi-square tests, Cramer's V , corresponding p- values and a logistic regression analysis. Results The results indicate that the magnitude of RAEs in this sport-unspecific, generic motor skill assessment was comparatively low within the 9–10-year-old age group. While statistically significant differences between age groups were observed, effect sizes were consistently small, suggesting limited practical relevance. Overall, the results indicate that raw values should be considered in addition to effect sizes for an appropriate interpretation of age-related differences. Discussion/Conclusion The gained findings show few meaningful differences in motor performance between age groups, but a practically relevant RAE can be negated. Conclusively, suggestions are given as to how the RAE could be countered in diagnostics to further reduce potential RAEs in talent diagnostics, including refined analytical approaches and mathematical adjustments.